Israel has tried several options, each of which has been condemned by vocal members of the international community, human rights groups and religious organizations - some of whom have been silent about the Hamas war crimes that precipitated the Israeli actions. Israel has tried economic sanctions, border controls, targeted attacks on terrorists and ground incursions. Each of these generally acceptable war measures carry with it the risk of some civilian casualties. The reason for this is that the distinction between combatants and civilians has deliberately been blurred by Hamas. Rockets are fired from densely populated areas, precisely in order to force Israel into choosing between allowing its own civilians to continue to be killed by its inaction, or taking actions that risk hurting killing some Palestinian civilians. Either way Hamas wins. If Israel does nothing, then Hamas accuses it of impotence. If it does something, then Hamas accuses it if disproportionally.
http://cgis.jpost.com/Blogs/dershowitz/entry/hamas_has_declared_war_on

See also:
Barak: Israel will keep on hitting murderers of Jews
http://www.haaretz.com/hasen/spages/963700.html

At least 15 Kassams pound western Negev, shattering calm
http://www.jpost.com/servlet/Satellite?cid=1205261318531&pagename=JPost%2FJPArticle%2FShowFull

Islamic Jihad’s Bethlehem heads killed
http://www.jpost.com/servlet/Satellite?cid=1205261315401&pagename=JPost%2FJPArticle%2FShowFull

http://www.ynetnews.com/articles/0,7340,L-3518471,00.html
Abbas: IDF operation in Bethlehem a barbaric crime